Re: thoughts from Tuesday telecon

Your notes have an example where a SPARQL query includes a bnode.    

The use of blank nodes in a SPARQL query is given two opposing meanings:

Meaning 1:

	2.4 Pattern Solutions

	Definition: Pattern Solution

	A pattern solution is a substitution function from a subset of the set
	of variables to the set of RDF terms, RDF-T. 

	The result of replacing every v in a graph pattern P by S(v) is written S(P).

	If variable v is not in the domain of S then S(v) is defined to be v.

	Definition: Query Solution

	Given query Q = (GP, DS, SM, R) then S is a query solution of Q if S is
	a pattern solution for GP matching dataset DS. 

Meaning 2:

	2.7 Blank Nodes

	Blank Nodes and Queries

	A blank node can appear in a query pattern. It behaves as a variable; a blank
	node in a query pattern may match any RDF term. 

Your use of blank nodes in a query corresponds to the first meaning, which, as
it is the formal definition of solutions, I take to be authoritative.  However,
as there is a second meaning, it would be better to be very explicit as to
which meaning you are using.


Peter F. Patel-Schneider